Radio device for secret communication



July 6, 1948. A. PTACEK 2,444,750

RADIO DEVICE FOR SECRET COMMUNICATION Fild Aug. 9, 1944 L g' aa (2 wa & Y 1

EgL 4a 49 4 7 46 l 1' I A l INVEN TOR.

A T TORNE Y Patented July 6, 1948 star S PATENT talent RADIO DEVICE FOR SECRET C'OIWMUNICATION Claims.

This invention relates to new and useful improvements in a radio device for secret communications.

More specifically, the invention proposes the construction of a radio device for secret communications characterized by a. radio sender and a radio receiver which are synchronized to send and receive on a constantly changing wave length permitting secret communications to be sent between the sender and the receiver and preventing them from being picked up by radio receivers which are not operating at the synchronized wave lengths.

A further object of the invention proposes providing the radio sender and the radio receiver with a knob or the like which may be turned back and forth for adjusting the variable condensers of these sets, and which are operated by electrically controlled synchronous motors which will cause the two devices to have their wave lengths changed in unison permitting the message sent out by the sender to be picked up by the receiver.

Still further the invention proposes the provision of a synchronous motor controlled by a reversing switch for causing the motor to rotate in one direction or the other to rotate the control knob back and forth, together with the provision of electrically controlled means for reversing the switch for the reasons above outlined.

It is a further object of this invention to construct a radio device for secret communication which is simple and durable and which can be manufactured and sold at a reasonable cost.

For further comprehension of the invention, and of the objects and advantages thereof, reference will be had to the following description and accompanying drawings, and to the appended claims in which the various novel features of the invention are more particularly set forth.

In the accompanying drawings forming a material part of this disclosure:

Fig. 1 is a schematic illustration of a radio device for secret communications constructed in accordance with this invention.

Fig; 2 is an enlarged detail showing a portion of the mechanism indicated in Fig. 1, and particularly-showing the intermittent drive to the tun-' ing condenser of the radio sender, this view taken on the line 22 of Fig. 3.

Fig. 3 is a schematic structural and wiring diagram of the radio sender.

A radio-device, for secret communications, according to this invention includes a radio sender Ill having an antenna H and having as here shown a knob 12 which may be turned back and forth for causing the radio sender to send messages out through the antenna 1 l on varying wave lengths. The device further includes a radio receiver I3 having an antenna M and havin as here shown a knob l5 which may be turned back and forth to cause the radio receiver to be adjusted to the wave length of the radio sender to pick up messages being sent out thereby.

Each of the knobs l2 and it is in the form of a gear attached to a shaft H3, connected for tuning a variable condenser, these condensers of like design, and of like capacitance on having their movable plates given like degrees of rotation. The condenser of the radio sender is indicated at It in Fig. 2. Automatic means, housed as indicated at H9 in Fig. 2, is provided for turning each of the gears 12 and I5 back and forth in short periods synchronized with each other. Said means, and the synchronizing means, are shown in detail in Fig. 3, taken with Fig. 2.

The automatic means in is alike for the radio sender I0 and for the radio receiver 13, and is characterized by a synchronous motor 20 with a transmission extended between the synchronous motor and the knob IE or 15. The automatic means I9 will be described in connection with the radio sender H! and its knob I2 and the same description applies to the automatic means for the radio receiver 1 3 and its knob 15.

The synchronous motor 2L has a projected driven shaft 2| and an adjacent shaft 22 which carries a gear 23. A sprocket chain 24 extends over the gear 23 and the gear l2 for turning the shaft H5 when the shaft 22 is rotated. A Geneva drive 25 is interposed between the driven shaft 2| and the shaft 22 for causin the shaft 22 to be intermittently driven from continuously driven shaft 2 I.

The type of Geneva movement shown is one long well-known as a satisfactory such movement which is reversible as to the direction of drive from the driving element to the driven element. The driving element, fixed on the shaft 2!, is a disc 46 having a projection carrying an upstanding driving pin 4|, for fractionally rotating a driven element 42 fixed on the shaft 22 to be intermittently fractionally rotated. As is familiar in the art of devices of this kind, following each complete revolution of element to said pin enters one of a plurality of radial slots in the driven element 42 spaced uniformly around the same, and thereby there is imparted to the driven element a rotation through since six are here shown. Between adjoining slots of the driven element 42, the periphery of the latter is arcuately concave to match the circularly rounded portion of the periphery of the driving element 40, so that for a part of each revolution of element 40, while the pin 4| is idle relative to a slot of the driven element 42, the latter is locked to the element 46 to prevent movement of the driven element 42. Beyond each opposite end of said circularly rounded portion of the periphery of the driving element 4 said element is arcuately concavely cut away so as not to interfere with sweep of the points of maximum diameter around the element 42, which points mark the outer ends of its radial slots. In a reversing Geneva of these slots the driven element is to be prevented, on a friction clutch, such as indicated at 43, to prevent; anypossibility of such shift for the duration; of, turning movement of the driving element; 40, following retreat of its pin 4| from a radial slotof element 42 and until ensuing lock of the element 42 against the circularly rounded portion of element 46.

A reversing switch 26 is provided for reversing the rotation of a synchronous motor 20 to cause the transmission to rotate the shaft [5 back and forth. The reversing switch 26 is normally closed at its upper pair of contacts by means of a retractile spring 21.

A coded rotary switch is provided for supplyandby take-off leads 5!, 52 and 53 chronous motor 30. nected, leads 54 and to the syn- 20 are con- 55, the former connected the rotary of -thi s;pa iroi; contacts 321s connected by a lead all 58 to another main lead 59. The synchronous motor 30 is connected to main lead 51 by lead 80, and also to the main lead 59 by a lead 6|.

Electro-magnetic means is provided for throwing the reversing switch 26 to overcome the spring 21 and open the upper pair of contacts and close the lower pair of contacts of switch 26. This electro-magnetic means comprises an electro-magnet 34 the coil of which is interposed in a circuit subdivision including leads 62 and 63, the latter lead connected to main lead 51. For governing energization of the electro-magnetic means a section on the drum 28 is provided with short metallic members 35 set into the insulation. material of the drum 28 each adapted to be engaged by and bridge a pair of adjacent fixedly mounted contacts 36. That one of the contacts of switch 36 other than the one connected in series with the coil of the electro-magnetlc means in lead 63 to main lead 51, is connected by a lead 64 to main lead 59. By this arrangement, the metallic members 35 are While I have illustrated and described the preferred embodiments as defined in the appended claims.

Having thus described my invention, what I claim as new, and desire to secure by United States Letters Patent is:

2. In combination with a radio"senderlhavingi a knob which may be turned back and forth for varying the wave lengths of the transmission and a radio receiver having a knob which may be turned back and forth for varying the wave lengths of reception, automatic means for turning each of said knobs back and forth in short periods synchronized with each other, comprising a synchronous motor, a transmission from said synchronous motor to said knob and including a Geneva drive, a reversing switch for said synchronous motor, a coded rotary switch having a section for supplying current to said synchronous motor in periods of difierent coded lengths of short intervals of time and also having a section for reversing said switch for periods of difierent coded lengths of short intervals of time, a synchronous motor for driving said rotary switch, an electric circuit for said first named synchronous motor and including in series said reversing switch and the first named section of said rotary switch, electro-magnetic means for throwing said reversing switch, and an electric circuit includin in series said electro-magnetic means and the second named section of said rotary switch, and the synchronous motors of each of said automatic means for turning said knobs being in synchronization with each other, said transmission comprising a continuously rotating shaft extending from said first synchronous motor, a shaft adjacent said driven shaft a gear mounted on said second shaft, said knob comprising a gear, a sprocket chain between the said gear, and said Geneva drive being mounted between said driven shaft and said second shaft.

3. In combination with a radio sender having a knob which may be turned back and forth for varying the wave lengths of the transmission and a radio receiver having a knob which may be turned back and forth for varying the wave lengths of reception, automatic means for turning each of said knobs back and forth in short periods synchronized with each other, comprising a synchronous motor, a transmission from said synchronous motor to said knob and including a Geneva drive, a reversing switch for said synchronous motor, a coded rotary switch having a section for supplyin current to said synchronous motor in periods of difierent coded lengths of short intervals of time and also having a section for reversing said switch for periods of different coded lengths of short intervals of time, a synchronous motor for drivin said rotary switch, an electric circuit for said first named synchronous motor and including in series said reversing switch and the first named section of said rotary switch, electro-magnetic means for throwing said reversing switch, and an electric circuit including in series said electromagnetic means and the second named section of said rotary switch, and the synchronous motors of each of said automatic means for turning said knobs being in synchronization with each other, and a contraction spring for closing said reversing switch in one direction.

4. In combination with a radio sender having a knob which may be turned back and forth for varying the wave lengths of the transmission and a radio receiver having a knob which may be turned back and forth for varying the wave lengths of reception, automatic means for turning each of said knobs back and forth in short periods synchronized With each other, comprising a synchronous motor, a transmission from said synchronous motor to said knob and including a Geneva drive, a reversing switch for said synchronous motor, a coded rotary switch having a section for supplying current to said synchronous motor in periods of different coded lengths of short intervals of time and also having a section for reversing said switch for periods of different coded lengths of short intervals of time, a synchronous motor for driving said rotary switch, an electric circuit for said first named synchronous motor and including in series said reversing switch and the first named section of said rotary switch, electro-magnetic means for throwing said reversing switch, and an electric circuit including in series said electromagnetic means and the second named section of said rotary switch, and the synchronous motors of each of said automatic means for turning said knobs being in synchronization with each other, said rotary switch comprising a drum of insulation material, said sections comprising spaced contact members mounted on the periphery of said drum and engaged by spaced contacts.

5. In combination with a radio sender having a knob which may be turned back and forth for varying the wave lengths of the transmission and a radio receiver having a knob which may be turned back and forth for varying the wave lengths of reception, automatic means for turning each of said knobs back and forth in short periods synchronized with each other, comprising a synchronous motor, a transmission from said synchronous motor to said knob and including a Geneva drive, a reversing switch for said synchronous motor, a coded rotary switch having a section for supplying current to said synchronous motor in periods of difierent coded lengths of short intervals of time and also having a section for reversing said switch for periods of different coded lengths of short intervals of time, a synchronous motor for driving said rotary switch, an electric circuit for said first named synchronous motor and including in series said reversing switch and the first named section of said rotary switch, electro-magnetic means for throwing said reversing switch, and an electric circuit including in series said electro-magnetic means and the second named section of said rot y switch, and the synchronous motors of each of said automatic means for turning said knobs being in synchronization with each other, said knobs being connected with the variable condensors of said radio sender and radio receiver for rotating these condensors to change the wave length.

ANNA P'rAonK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,325,574 Nichols Dec. 23, 1919 1,555,633 Burch et a1. Sept. 29, 1925 1,607,485 Schmidt Nov. 16, 1926 1,816,953 Bown Aug. 4, 1931 

